The Saxby Gale of 1869

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  • Passamaquoddy Bay, Maine, an inlet of the Bay of Fundy, in a painting by the French artist Victor De Grailly (1804-1889).

    Estimated path of the 'Saxby Gale' or 'Allison Hurricane' in October 1869.

    Photo: Andrew Matthews/PA Archive/Press Association Images

  • The Saxby Gale of 1869
    03.05.2012 15:24

     

    In early October 1869 a hurricane moved NNE’wards off the eastern seaboard of the USA, crossing Cape Cod, Massachusetts, and then making proper landfall in Maine, north-eastern USA, and New Brunswick in the Canadian Maritimes early on the fifth day of the month.

    Evidence suggests that at its most powerful it was a Category 2 hurricane, implying steady wind speeds of 154 to 177 kilometres per hour (96 to 110mph). It dumped torrential rainfall, caused floods across the north-eastern States and the Maritimes, destroyed homes and accounted for at least 37 fatalities.

    A familiar enough story, you might think, but this was in the early days of meteorology as a modern science; after all, the world’s first weather forecast had been published in The Times only eight years previously. The term ‘hurricane’ had not yet been formally coined, and so the storm became known as the Saxby Gale.

    Why, though? Who was Saxby?

    To answer those questions we have to travel back a further year to December 1868 and read a letter to the London Standard penned by Stephen Martin Saxby, a Royal Navy lieutenant who developed the ‘Saxby Weather System’, which purported to forecast storms based on lunar and solar influences.

    As part of that letter he wrote: “I now beg leave to the state, with regard to 1869, that at seven a.m., on October 5, the moon will be at that part of her orbit which is nearest to the earth. Her attraction will, therefore, be at its maximum force. At noon of the same day the moon will be on the earth's equator, a circumstance which never occurs without mark atmospheric disturbance, and at two p.m. of the same day lines drawn from the earth centre would cut the sun and moon in the same arc of right ascension (the moon's attraction and the sun's attraction will therefore be acting in the same direction); in other words, the new moon will be on the earth's equator when in perigee, and nothing more threatening can, I say, occur without miracle.”

    In a follow-up on 16 September 1869 he wrote that “one is justified in expecting (to say the least) quite as great an atmospheric disturbance early in October as we have had since 6th inst. […] The warnings apply to all parts of the world; effects may be felt more in some places that in others. It is painful to have to forebode evil; but better thus than to merit self-reproach under circumstances which might lead to permanent regrets.”

    What he was saying here was that the gravitational effect of the moon at perigee, combined with the lesser pull of the sun, would provoke abnormally high spring tides. Which is all fine and dandy but eminently predictable by anyone with the relevant astronomical data.

    He further implied that should there be a coastal storm at the same time then the effects might be profound, as indeed in this case they turned out to be. The Bay of Fundy, between New Brunswick and Nova Scotia, Canada, has the highest tidal range in the world, and this was exacerbated not only by the spring tide but also by the hurricane’s storm surge funnelling up from the southwest.

    However, he did not forecast just where on Earth any potential storm might strike: “The warnings apply to all parts of the world…”, he said, a statement which is of little practical use. Storms can occur at any time almost anywhere, and there was no indication that Maine and New Brunswick in particular should prepare themselves.

    Digging deeper, though, we find that on top of this vague assessment a remarkably prescient and specific forecast was issued by a Canadian meteorologist, Frederick Allison, in a letter to the Halifax (Nova Scotia) Evening Express.

    On 30 September he wrote: “I believe that a heavy gale will be encountered here on Tuesday next, the 5th Oct., beginning perhaps on Monday night, possibly deferred as late this Tuesday night; but between those two periods it seems inevitable. At its greatest force the direction of the wind should be South West; having commenced at or near South. Should Monday, the 4th, be a warm day for the season, an additional guarantee of the coming storm will be given. Roughly speaking, the warmer it may be on the 4th, the more violent will be the succeeding storm.”

    Reference to warmth gives pause to wonder whether Allison had some inkling of the nature of tropical storms as opposed to strong mid-latitude depressions. Was there some skill in this forecast? Did reports from ships perhaps give him an idea that a storm was brewing in the western Atlantic? It seems unlikely given the likely slowness of communication. Did he just strike lucky?

    There is no record of any other of his forecasts, so we will never know how skilled a forecaster he might have been. Perhaps we should bestow the benefit of the doubt, and given the relatively rudimentary state of meteorological science at the time it would have been a very good forecast.

    But whether the greater part was played by luck or skill, the storm should clearly be known not as the Saxby Gale but as the Allison Hurricane.

    By: Stephen Davenport